A Lesson in Perfection: 1959 Ariel Square Four

Restorer Gary Athey found the Ariel Square Four he’d always wanted, and then rebuilt it to his own specification.

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by Jeff Barger

Engine: 997cc air-cooled OHV “square” 4-cylinder, 65mm x 75mm bore and stroke, 7.2:1 compression ratio, 42hp @ 5,500rpm (claimed)

Top speed: 105mph (approx.)

Carburetion: SU, variable choke

Transmission: 4-speed, chain final drive

Electrics: 6v, coil and breaker points distributor ignition

Frame/wheelbase: Single downtube steel cradle/56in (1,422mm)

Suspension: Telescopic forks front, plunger rear

Brakes: 7in (178mm) drum front, 8in (203mm) drum rear

Tires: 3.25 x 19in front, 4 x 18in rear

Weight (wet): 435lb (197kg)

Seat height: 31in (787mm)

Fuel capacity: 6gal (22.7ltr)

From a very young age, motorcycle enthusiast Gary Athey worked diligently under his father’s tutelage at Athey’s Garage in Green Bay, Wisconsin.

Started in 1946 by his dad, the garage looked after machining and rebuilding all manner of engines, transmissions and differentials — anything that required specialized equipment to bore cylinders, cut valve seats, machine crank journals or simply change oil and filter and perform a tune up.

“When I was 16, I remember a customer rode into the repair shop on an Ariel Square Four,” Gary explains. “I was captivated by the sight and thought maybe one day I’d own one.” Fast forward to 1998. Gary was still thinking about an Ariel Square Four, but more than that, he was talking about the machines, too. “My wife, Virginia, said to me, ‘Well, find one’,” Gary recalls.

Needing no further encouragement, Gary started looking for a Square Four but had little luck locating one that was for sale near his Green Bay home. He finally learned of a Square Four that was available at Baxter Cycle in Marne, Iowa, and Gary made plans to go take a look.

“But just a couple of days before I was going to go, I ran into a guy I knew who worked part time at a Harley-Davidson dealership,” Gary continues. “He asked me what I was working on, and what I was looking to do next.”

The topic of the Ariel Square Four came up, and Gary’s acquaintance said he knew of one just down the road. Together, they went and knocked on the door and were welcomed into the owner’s climate-controlled building where there was a large collection of motorcycles including BSAs, Nortons, Triumphs and Harley-Davidsons. But Gary was most interested in the 1959 Ariel Square Four that, to his delight, had a Watsonian sidecar attached.

While not to everyone’s liking, Gary has owned and maintained several motorcycles with sidecars, and says he owned his first combination when he was around 14. He’d load up the sidecar and go hunting for a weekend, or, in his younger years, fill the tub with ice and bring a keg of beer to a party.

“He showed me the Ariel and sidecar, and while I’d been led to believe he didn’t usually sell anything, he surprised me at the end of the conversation when he asked if I’d be interested in buying it,” Gary says. “I went straight home, got my trailer and some money and went back to pick it up.”

Apparently, the Ariel and sidecar had been bought four years earlier in 1994 at a vintage motorcycle auction in Las Vegas. Purportedly mechanically rebuilt, the Ariel and sidecar had not been used while in the seller’s collection.

“I never take anybody’s word about the mechanical status of a machine,” Gary tells us, and continues, “As soon as I got it home, I had the entire thing completely apart, removing every nut and bolt down to the cranks.”

In the beginning

Originally designed by Edward Turner in 1925, his square four concept was as simple as two parallel twin engines coupled together with an overhead camshaft rotated by chain. Lore has it that Turner, who had been operating a motorcycle shop in Peckham, London, began showing his square four drawings, and another set featuring an overhead cam single, around to the British motorcycle industry. BSA exhibited some initial interest, but didn’t follow up, and that’s when, in 1928, Turner met with Ariel sales manager Vic Mole. Mole was sufficiently impressed to bring Turner to the attention of Jack Sangster, Ariel’s manager.

By November 1928, Turner was working in the design studio with Valentine Page as his boss. Bert Hopwood joined shortly after as an assistant, and this team transformed Turner’s design into a prototype engine in 18 months.

The prototype was a compact powerplant that held four pistons in a square layout, featuring fore and aft crankshafts geared together with helically cut teeth on each central flywheel. The rear flywheel gear in turn delivered power to a unit-construction 3-speed transmission. Bore and stroke was 51mm x 61mm and the 4-cylinder engine was small enough to fit in Ariel’s 250cc Colt frame — a model that had a sloping cylinder that fit between two widely spaced front frame downtubes.

This layout didn’t come to fruition, however, as Sangster realized it would prove costly to build in full scale production. Instead, the unit construction idea was dispensed with and a more traditional separate Burman transmission was employed. To make this work, the rear crankshaft on the left side of the engine was made longer to accept a sprocket to take power pulses via chain to the clutch and gearbox. The engine still had Turner’s chain driven overhead cam and another chain turned a magneto located behind the cylinders. Now somewhat beefier than anticipated, the 498cc engine and separate transmission still fit into one of Ariel’s single-cylinder frames with splayed front downtubes, this one the 500cc sloper SG31.

First shown late in 1930 at the Olympia Motorcycle show, the Square Four was launched for the 1931 model year. Initially offered as the 498cc model, to give more power to tug along a sidecar, the Square Four was enlarged to 601cc in 1932 and was available in both sizes that year. In 1933, only the 600 was sold.

By 1936, Turner had moved to Triumph and Frank Anstey took over as Ariel’s chief designer. Under his supervision, for 1937 Ariel revised the 4-cylinder engine by changing the crankcase from horizontally split to vertically split and replaced the overhead cam with one located in the center of the crankcase. The crankshaft coupling gears moved outboard of the crankcase and were hidden behind a left side cover. Overhung connecting rod big ends made way for crankshafts that were widened to run in timing side bushes and drive side bearings — the big ends now split to accept bearing shells.

With the cam centrally located, short pushrods were employed to actuate the overhead valves. Cylinders and cylinder head were in cast iron, but the rockers themselves were housed in a separate alloy box. At this point, the engine was no longer truly “square” but more rectangular in its cylinder layout but Rectangular Four doesn’t have the same marketing ring to it.

Significantly important, while still producing a 600cc model until World War II, bore and stroke of the engine was taken to 65mm by 75mm to provide 997cc’s — and from 1945 on the Square Four was only available in the larger capacity. As the 1,000cc 4G model, Ariel equipped the Square Four with telescopic forks in 1946 and next updated the model for 1949 when the cast iron barrel and head was replaced by alloy components to create the Mark I version.

Mark II Square Fours in 1953 gained four distinctive exhaust header pipes and a bench-style dual seat replaced the sprung solo saddle. From that point on only minor changes, such as adding a 7-inch full-width alloy front hub, were made to the motorcycle until the end of the line — which came in 1958 with some being sold into 1959.

On the side

As for the sidecar maker Watsonian, that British company was founded in 1912 by Thomas Fredrick Watson. First named the Patent Collapsible Sidecar Company, and then the Watsonian Folding Sidecar Company Ltd, the “folding” aspect is due to the fact Watson built a sidecar that could be collapsed towards the motorcycle, allowing the outfit to squeeze down narrow pathways and laneways to reach the backyards of English terrace homes.

The concept caught on, and Watsonian went on to produce many styles of chairs and, some 108 years later, continues to do so. Watsonian Sidecar is in Gloucestershire, England, and now operates under the name Watsonian Squire Ltd. The company builds a number of different models, many based on some of its own historic designs.

Unfortunately, Gary does not know the exact model name of the chair he has, but it looks very similar to the Grand Prix sidecar that’s currently offered by Watsonian.

Going back together

Gary won’t take anyone’s word about the condition of a motorcycle because, as he says, “I made my living rebuilding automobile, truck and tractor engines for customers, and my dad’s motto was always, ‘Make it as perfect as you can.'”

While he says it was apparent someone had gone through the Ariel Square Four’s engine and gearbox, none of the hard work had been done and Gary took it to the next level. To satisfy himself, he reground the crank journals and installed new shell bearings in the four light alloy connecting rods. A new cam went in the bottom end and Gary also altered the breathing system to improve overall performance. The cylinder block was machined to accept brand new pistons and rings, and new valves and springs went into the re-worked cylinder head. He also upgraded the double-gear Ariel oil pump to one produced by Morgo.

The transmission, Gary says, was in good condition, but he closely inspected all the gears and replaced every bush and bearing as a matter of course. The wheels were rebuilt with new U.K.-made chrome rims laced to the restored hubs with stainless steel spokes.

Many of the parts and pieces required, including a new wiring harness, came from Draganfly Motorcycles in the U.K. (draganfly.co.uk). All of this work was done in the days before the prevalent use of the internet, and Gary recalls writing many letters and occasionally making a long-distance phone call to order parts or simply seek advice.

A fresh coat

When Gary bought the Ariel, it was painted what is known as Bright Cherokee Red, a North American export-only color. He had the sidecar tub and steel motorcycle fenders, toolbox and headlight nacelle and fork covers sprayed, as well as the gas tank that was first meticulously re-chromed before the paint and pinstriping was applied. The motorcycle and sidecar frames were painted black.

Gary’s aware that some aspects of his Ariel Square Four aren’t to factory specification, including the chromed rear stand, fork lower sliders and the myriad fender brackets. All chrome, with the exception of the large bar that runs around the sidecar, was renewed.

The saddle on the motorcycle and the sidecar upholstery itself was in good shape, so it was left alone, but the basket on the sidecar’s rack received a new pair of leather straps.

After two years of work, Gary says his Ariel Square Four and Watsonian sidecar was ready to fire up and hit the road — which isn’t something that usually happens with many of his restorations. Don’t think that he doesn’t usually finish a bike, because he always does.

His philosophy, however, is to build up bikes the way he likes them with all fresh machine work and brand-new components, while not being overly concerned about deviations from stock and without ever firing them up to hear them run.

But the Ariel — this one is a runner. And, according to Gary, it’s an easy starter. In fact, Gary says one might think there’s something wrong when kicking it over.

“It’s so nice to kick and get started,” he says. “You’d say the valves are burnt or something else is wrong to take away compression, but it just fires right up. It’s one of my favorite bikes and I’ve probably put about 1,000 miles on it.” MC

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